Dental apparatus with a number of dental instruments connected to a common control circuit and a common operator unit

ABSTRACT

In a dental apparatus, in which each of a number of instruments is controlled by a control circuit common to the instruments, which are connected with a common operator unit having a control member which is movable in planar directions out of a home position, auxiliary functions not related to the instrument operation may be carried out by means of the common operator unit by switching the apparatus to a second mode of operation, when all the instruments assume respective resting positions in an instrument carrier. Moreover, also auxiliary functions directly related to the instrument operation may be carried out by the common operator unit in a first mode of operation by actuating the control member thereof with a movement different from the instrument energizing movement. The movement for energizing such an auxiliary function may have another direction and/or a shorter duration than the instrument energizing movement. In addition, the apparatus may be constructed to energize an air blow automatically after each operation of a drilling instrument when the control member of the common operator unit returns to the home position in the first mode of operation.

This is a division of application Ser. No. 272,061, filed June 9, 1981,now U.S. Pat. No. 4,430,062, issued Feb. 7, 1984.

The present invention relates to a dental apparatus of the kind, inwhich each of a number of instruments is controlled from a controlcircuit which is common to the instrument and is connected with a commonoperator unit such as a foot contact having a movable control member.

With a view to simplification in respect of labor and increase of safetyin the operation of the dental instruments in such an apparatus, effortshave been made in recent years towards an increased extent ofautomatization of the operation functions related to the use of theinstrument, so that the dentist is liberated to a great extent fromseparate hand or foot operation of individual control members for theinstruments.

It is the object of the invention to provide a dental apparatus offeringfurther simplification in respect of labor and improved safety in theperformance of an increased number of operation functions in connectionwith the dentist's work.

According to a first aspect of the invention, a dental apparatus isprovided, comprising a number of dental instruments arranged removablyin individual positions in the carrier, instrument removal signalgenerators individually associated with each of the instrumentpositions, a control circuit common to the dental instruments, aninstrument selector device incorporated in said control circuit andconnected to the removal signal generators an instrument energizing andcontrol device in the control circuit for energizing and controllingonly one instrument at a time when selected by said selector device, anoperator unit common to said instruments for controlling theenergization and control of the selected instrument by the energizingand control means, the operator unit comprising a control member whichis movable out of a home position to perform an instrument energizingmovement, means in the control circuit for sensing the instrumentenergizing movement and actuating the energizing and control means inresponse thereto, selectively actuable function energizing devices foractuating auxiliary functions during a dental treatment, which are notrelated to the operation of the dental instruments; at least one suchfunctioning energizing device being incorporated in the common controlcircuit, a mode switching device incorporated in the common controlcircuit and controlled by the instrument selector device for switchingthe dental apparatus between first and second modes of operation inresponse to at least one instrument being removed from its position orall instruments assuming their respective positions in the instrumentcarrier, respectively, first and second input control units incorporatedin the common control circuit and being connected to the operator unitby the mode switching device in said first and second mode respectively,the first input control unit being connected with the instrumentenergizing and control means and the second input control unit beingconnected with the at least one function energizing device forenergizing the auxiliary function governed by the device in response tomovement of the control member of the operator unit in said second modeof operation.

The invention is primarily based on the recognition of the fact that thedentist's treatment of a patient in addition to the control functionsdirectly related to the operation of the dental instrument involves anunber of further auxiliary functions which are not directly related tothe instrument operation and have hitherto been actuated by manualoperation of separate member for each of the functions.

As examples of auxiliary functions not related to the instrumentoperation which in the apparatus according to the invention mayadvantageously be activated by means of the common operator unit in thesecond mode of operation in which all the dental instruments assumetheir respective positions in the instrument carrier, mention could bemade of filling of water in the patient's rinsing glass, activation of afountain flush for the spittle from the patient, generation of a callsignal for the dentist's assistant and adjustment of the patient's chairby height control or change of the relative positions of seat, back andleg supports.

An increase of the number of auxiliary functions not related to theinstrument operation which in the second mode of operation can beincorporated in the control circuit and the common operator unit may beattained in that the control member of the operator unit is disposed forplanar movement in opposite directions out of the home position forinstrument operation and is further movable in the home position in atleast one direction perpendicular to the planar movement, the modeswitching device being constructed to supply a number of differentenergizing signals to the second input control unit in the second modeof operation corresponding to the number of directions of movement ofthe control member out of said home position, a number of functionenergizing devices corresponding to the number of different energizingsignals being connected to the second input unit for actuatingindividual different ones of said auxiliary functions in response toindividual different ones of the energizing signals.

According to a second aspect of the invention, a dental apparatus isprovided comprising an instrument carrier with a number of dentalinstruments arranged removably in individual positions in the carrier,instrument removal signal generators individually associated with eachof the instrument positions, a control circuit common to the dentalinstruments, an instrument selector device incorporated in the controlcircuit and connected to the removal signal generators, an instrumentenergizing and control device in the control circuit for energizing andcontrolling only one instrument at a time when selected by the selectordevice, an operator unit common to the instruments for controlling theenergization and control of the selected instrument by the energizingand control means, the operator unit comprising a control member whichis movable out of a home position to perform an instrument energizingmovement, means in the control circuit for sensing the instrumentenergizing movement and actuating the energizing and control means inresponse thereto, selectively acutable function energizing devices foractuating auxiliary functions related to the operation of the dentalinstruments, at least one such function energizing device beingincorporated in the control circuit, an input control unit incorporatedin the control circuit and connected with the instrument energizing andcontrol means as well as the operator unit to sense the instrumentenergizing movement as well as a movement of the control memberdifferent from the instrument energizing movement, the at least onefunction energizing device being connected to the input control unit tobe actuated therefrom in response to the different movement of thecontrol member.

In this second aspect, the invention is primarily based on therecognition of the fact that the dentist's treatment of a patient inaddition to the control functions directly related to the operation ofthe dental instrument involved a number of further auxiliary functionswhich are directly related to the instrument operation and have hithertobeen actuated by manual operation of separate numbers for each of thefunctions.

As examples of auxiliary functions related to the instrument operationwhich by means of the apparatus according to the invention mayadvantageously be energized by a movement of the control member of thecommon operator unit different from the instrument energizing movement,mention could be made of control of the composition of water and air ina coolant which by use, for example, of a drilling instrument is sprayedby means of a spraying device provided directly on the instrument or thegeneration of an air blow for drying a cavity produced with a drillinginstrument.

In an embodiment of the apparatus according to the second aspect of theinvention, the movement of the control member of the operator unitdifferent from the instrument energizing movement may be realized inthat the control member of the operator unit is disposed for planarmovement in opposite directions out of the home position for instrumentoperation and is further movable in the home position in at least onedirection perpendicular to the planar movement, the operator unit beingconstructed to transmit a number of different energizing signals to theinput control unit corresponding to the number of movement directions ofthe control member out of the home position, the input control unitbeing constructed to actuate the function energizing device in responseto the energizing signal transmitted by the operator unit in response tosaid perpendicular movement of the control member. This embodiment isparticularly suitable for a function energizing device in the form of acoolant control device.

As another possibility, the movement of the control member differentfrom the instrument energizing movement may be realized in that a timingdevice is connected to the input control unit for measuring the durationof the planar instrument energizing movement of the control member, theinput control unit being constructed to actuate the instrumentenergizing and control means only in response to a duration of themovement exceeding a prescribed minimum duration and to actuate thefunction energizing device in response to a shorter duration of themovement of the control member. This embodiment is particularly suitablefor a function energizing device in the form of an air blow energizingdevice.

In a preferred embodiment of this second aspect of the invention, adental apparatus is provided, comprising an instrument carrier with anumber of dental instruments arranged removably in individual positionsin said carrier, instrument removal signal generator individuallyassociated with each of the instrument positions, a control circuitcommon to the dental instruments, an instrument selector deviceincorporated in the control circuit and connected to the removal signalgenerator, an instrument energizing and control device in the controlcircuit for energizing and controlling only one instrument at a timewhen selected by the selector device, an operator unit common to theinstruments for controlling the energization and control of the selectedinstrument by the energizing and control means, the operator unitcomprising a control member which is movable out of a home position toperform an instrument energizing movement, means in the control circuitfor sensing the instrument energizing movement and actuating theenergizing and control means in response thereto, selectively actuablefirst and second function energizing devices for actuating a first and asecond auxiliary function related to the operation of the dentalinstruments being incorporated in the control circuit, an input controlunit incorporated in said control circuit and connected with theinstrument energizing and control means and the first and secondfunction energizing devices as well as the operator unit, the controlmember of the operator unit being disposed for planar movement inopposite directions out of the home position for operation of the dentalinstruments and being further movable in the home position in at leastone direction perpendicular to the planar movement, the operator unitbeing constructed to transmit a number of different energizing signalsto the input control unit corresponding to the number of movementdirections of the control member out of the home position, a timingdevice being connected to the input control unit for measuring theduration of the planar movement of the control member, the input controlunit being constructed to actuate the first function energizing devicein response to the energizing signal transmitted by the operator unit bythe perpendicular movement of the control movement and to actuate theinstrument energizing and control means and the second functionenergizing device in response to a duration of the planar movement ofthe control member exceeding or being shorter, respectively , than aprescribed minimum duration.

In this combination it may be advantageous in connection with a functionenergizing device in form, for example, of a coolant control device thatthe timing device is constructed to measure the duration of theenergizing signal also for said perpendicular movement of the controlmember, the first function energizing device being constructed forcyclic adjustment of its respective auxiliary function through a numberof control steps, the input unit being constructed to actuate the firstfunction energizing device for a single step adjustment in response to aduration of the movement of the control member shorter than theprescribed minimum duration and through a number of steps in response toa longer duration of the movement of the control member.

According to a third aspect of the invention a dental apparatus isprovided comprising at least one drilling instrument and an operatorunit with a control member which is movable against spring action out ofhome position for energizing and controlling the drilling instrument, aninstrument energizing device connected between the drilling instrumentand the operator unit, a water spraying device and an air blowing deviceprovided on the drilling instrument, water and air supplies connectedwith the water spraying and air blowing devices, valve devices arrangedbetween the water and air supplies and the water spraying and airblowing device, and water spray and air blow energizing devicesconnected to the valve devices and the instrument energizing device forproducing a coolant spray during operation of the instrument, aselectively actuatable air blow energizing device with an associatedvalve device being provided at least for the air blowing device, theselectively actuatable air blow energizing device being connected to theoperator unit for automatically supplying an opening signal to itsassociated valve device in response to the control member of theoperator unit returning to the home position following a movement out ofthe position.

In a preferred embodiment of this third aspect of the invention thedental apparatus is constucted so that a timing device is connectedbetween the selectively actuatable air blow energizing device and theoperator unit for measuring the duration of the movement of the controlmember out of the home position and the selectively actuatable air blowenergizing device is constructed to produce first or second openingsignals for the associated valve device in response to the duration ofthe movement of the control member being shorter or longer,respectively, than a prescribed minimum duration.

In connection with this embodiment, if the control circuit is contructedso that energizing of the drilling instrument is only taking place, whenthe duration of the movement of the control member out of the homeposition exceeds the prescribed minimum duration, the drillinginstrument may serve at a shorter duration of the movement of thecontrol member as a separate air blowing device to produce an air blow,for example, in advance of a drilling operation.

In order to obtain a more efficient drying after a drilling operation,for example, with accompanying coolant spray, the timing device ispreferably constructed so that the first opening signal comprises asingle opening pulse, whereas the second opening signal comprises atleast two succeeding opening pulses of different duration.

In the following, the invention will be explained in further detail withreference to the schematical drawings, wherein

FIG. 1 is a simplified perspective view of a dentist's stand including adental apparatus according to the invention;

FIG. 2 is a simplified schematical diagram of an embodiment of thedental apparatus;

FIG. 3 is a flow chart illustrating the operation of the dentalapparatus; and

FIG. 4 shows a modification of the dental apparatus according to theinvention.

The dentist's stand shown in FIG. 1 comprises a patient's chairdesignated as a whole by 1. A stationary support 2, which is onlyschematically illustrated, is connected with an instrument carrier 3having a number of separate positions for dental instruments 4 to 7. Ina manner known per se, these instruments may comprise, for example,drilling instruments driven either by a motor having two directions ofrevolution and a continuously variable rotational speed, or by an airturbine which may have a fixed direction of revolution and rotationalspeed. As shown for the instrument 6, such drilling instruments may beprovided with a device 8 for spraying a coolant composed of water andair during operation and for providing a pure air blow for drying acavity made by means of the drilling instrument. The energy supply tothe instruments 4 to 7 takes place through electric cables or air hoseswhich in the embodiment are carried over spring-biased pivot arms 9 to12, for each of which a microcontact is provided in a manner, notillustrated, for generating a removal signal when the relevantinstrument is lifted off from its position in the instrument carrier.

Finally, the treatment stand comprises a rinsing assembly with afountain 13, a support 14 for a rinsing glass 15 and a water fillingdevice 16.

For performing all control functions directly related to the operationof the instruments 4 to 7, as well as a number of further auxiliaryfunctions not directly related to the instrument operation, thetreatment stand further comprises a single common operator 17 which inthe embodiment shown takes the form of a foot contact. The foot contact17 has a control member 18 in the form of a projecting arm which mayperform a planar horizontal movement to both sides out of a central homeposition, on one hand, and may perform, on the other hand, a movementperpendicular thereto when assuming the central position, such as avertical downwards movement.

The schematic diagram in FIG. 2 illustrates the principal structure ofthe signal processing and actuating circuits of the dental apparatus.The instruments in the instrument carrier 3 are shown schematically byinstrument blocks 19 to 22, the construction of which is onlyillustrated for the instrument block 19 associated with the instrument6, since the remaining instrument blocks 20 to 22 are constructed, inprinciple, in a similar manner. The instrument blocks 19 to 22 areconnected to a common control circuit 23, to which also the commonoperator unit 17 is connected.

The microcontact 6a associated with the pivot arm 11 for the instrument6 is connected in the control circuit 23 to an instrument selectordevice 24, to which the corresponding microcontacts for the remaininginstruments are also connected The instrument selector device 24 may beconstructed in such a way that only one of the instruments 4 to 7 may beactuated at a time, i.e. by actuation of any instrument, a blocking isestablished against actuation of the other instruments independent oftheir possible removal from the instrument carrier 3. Thereby, it ispossible, for example, for the dentist's assistant to prepare anotherinstrument for subsequent use independent of the dentist's use of aninstrument.

Thus, since it will be recorded in the instrument selector device 24 atany time, whether one or more of the instruments 4 to 7 are lifted off,or all instruments assume their respective positions in the instrumentcarrier 3, the instrument selector device 24 is connected, in accordancewith the invention, with a mode switching device 25 for switching thedental apparatus between a first mode of operation, in which at leastone of the instruments 4 to 7 is lifted off, and a second mode ofoperation, in which all instruments assume their respective positions inthe instrument carrier. In FIG. 2, the mode switching device 25 isillustrated purely schematically by two-position switches 26 and 27. Ina similar manner, the construction of the operator unit 17 isillustrated purely schematically with a contact 28 which is actuated bythe vertical downwards movement of the control member 18 and isconnected to the switch 26 in the mode switching device 25 together witha voltage divider 29, the displaceable tapping of which is connected tothe switch 27 in the mode switch device 25 and assumes a positioncorresponding to the position of the control member 18 in the horizontalmovement.

In the first mode of operation, in which at least one of the instruments4 to 7 is lifted off, the switches 26 and 27 are connected to a firstinput control unit 30, by means of which the operator unit 17 isconnected for actuation of instrument energizing and control means 31for an instrument selected for energization by the instrument selectordevice 24. For use in connection with instruments which like theinstrument 6 shown in the figure are provided with a device 8 forspraying a coolant during operation, and for air blowing, magnet valves33 and 34 actuating the supply of water and air in the coolant areconnected to the energizing and control means 31, on one hand, and, onthe other hand, a coolant control device 32 acting on contacts 32a and32b in the instrument block for releasing or blocking each of the magnetvalves 33 and 34, as well as an air blow energizing device 31a acting ona magnet 34a to produce the above mentioned air blow are connected tothe input control unit 30.

When a drilling instrument driven by an electric motor and having twopossible directions of revolution and a continuously variable rotationalspeed is energized by horisontal movement of the control member 18 outof the central position, the value of the voltage signal supplied fromthe voltage divider 29 through the switch 27 to the input control unit30 corresponding to the movement of the control member 18 out of thehome position serves for controlling the rotational speed of theselected drilling instrument via the energizing and control means 31.This speed control may advantageously be non-linear, so that on themajor part of the movement of the control member 18 out of the centralposition, a relatively slow speed increase takes place and a strongincrease towards full speed is not accomplished until near the extremeposition. The sign of the voltage signal corresponding to the directionof the planar horizontal movement of the control member 18 out of thecentral position actuates the energizing and control means 31 toenergize the drilling instrument in one direction of revolution or theother. Since in most normally occurring treatments dental drillinginstruments must rotate clockwise, and counter-clockwise rotation isonly prescribed for certain special treatments, an alarm device 35 may,furthermore, be connected to the input control unit 30 for supplying,for example, an acoustic alarm signal when the control member 18 hasbeen moved to the side corresponding to counter-clockwise rotation ofthe drilling instrument, for example to the left.

If the instrument selected by means of the instrument selector device 24is an air turbine powered drilling instrument, the control by means ofthe control member 18 may be an on-off control by which the instrumentis energized with the prescribed direction of revolution and rotationalspeed independent of the direction of movement of the control member 18.

If a coolant spraying device is associated with a drilling instrumentselected by means of the instrument selector device 24, said sprayingdevice is actuated simultaneously with the energization of theinstrument from the energizing and control means 31.

In the case of all the instruments 4 to 7, assuming their respectivepositions in the instrument carrier 3, the mode switching device 25 isswitched by means of the instrument selector device 24 to the otherposition of each of the switches 26 and 27, the operator unit 17 isconnected to a second input control unit 36, to which functionenergizing devices 37, 38 and 39 for energizing auxiliary functions notrelated to the instrument operation are connected.

As examples of such auxiliary functions, mention could be made ofactivation of a flushing device associated with the fountain 13 shown inFIG. 1 by means of a magnet valve 40 energized by the functionenergizing device 37, activation of the water filling device 16 shown inFIG. 1 by means of a magnet valve 41 energized by the functionenergizing device 38 and generation of a call signal for the dentist'sassistant by remote energization of an acoustic signal generator 42, forexample, by means of the function energizing device 39.

The above mentioned auxiliary functions are activated by the three abovementioned control movements of the control member 18 of the operatorunit 17, i.e. the two oppositely directed horizontal movements out ofthe central position and the vertical downwards movement in the centralposition. The actuation may take place, for example, in such a mannerthat horizontal movement in one direction results in a time limitedenergization of the magnet valve 40, whereas horizontal movement in theother direction results in a time-limited energization of short durationof the magnet valve 41 followed by time-limited energization of themagnet valve 40, and vertical downwards movement results in energizationof the signal generator 42.

In FIG. 2 a further possible movement of the control member 18 of theoperator unit 17 in addition to the two oppositely directed horizontalmovements and the vertical downwards movement is illustrated in dashedlines, namely a horizontal inwards movement of the control member 18 inits central position perpendicular to the above mentioned movements.Thereby, a contact 43 is closed, which is connected through a switch 44in the mode switching device 25 to the input control unit 36 in thesecond mode of operation and causes the input control unit 36 to actuatea function energizing device 45 for energizing a fourth auxiliaryfunction. As an example of such a function, adjustment of the patient'schair 1 in FIG. 1 could be mentioned. The patient'chair 1 comprises aseat 46 which is adjustably connected with a back 47 and a leg support48, adjusting means for height control and control of the relativepositions of seat and back being associated with the patient's chair. Itis known in the art to design these adjusting means in such a way thatthe chair is usually moved between two fixed adjustments, viz. atreatment position with the back laid down to a lying position of thepatient and a raised position for use when the patient enters or leavesthe chair or uses the rinsing glass 15 and the fountain 13. By means ofthe additional movement possibility for the control member 18 and theactuation of the control circuit 23 associated therewith, a simpleswitching between the two positions without operation of separateoperating members is obtained.

In addition to the described switching of the apparatus between firstand second modes of operation and the possibility resulting therefromfor actuating a number of auxiliary functions not related to theinstrument operation, use is made in the embodiment shown of awide-going automization of the instrument operation per se by allowingalso auxiliary functions like coolant control and actuation of an airblow to be performed by means of the common control circuit 23 and thecommon operator unit 17 connected therewith. For this purpose, a timingdevice 49 may be connected to the input control unit 30 to measure inthe first mode of operation the duration of a voltage signal from thevoltage divider 29 through the switch 27 generated by horizontalmovement of the control member 18 as well as a signal from the contact28 through the switch 26 generated by vertical downwards movement of thecontrol member 18.

However, the input control unit 30 may also be constructed so that saidair-blow is only energized by movement of the control 18 to one side,for example to the right, whereas a short movement of the control member18 to the other side energizes a flashing spray comprising water as wellas air in a predetermined mixing ratio.

The coolant control device 32 is constructed for stepwise control of thecombination of water and air, respectively, in the coolant by means ofthe contacts 32a and 32b, for example, in four control stepscorresponding to neither water nor air (no coolant), water alone, airalone, or both water and air in a predetermined cyclic order ofsuccession of the control steps. The input control unit 30 co-operateswith the timing device 49 in such a manner that by actuating of thecontact 28 with a duration shorter than the predetermined minimum time,the coolant control device 32 will be actuated to a single step changeof the water-air combination, whereas in case of a prolonged actuationof the contact 28, the coolant control device 32 will be actuated to gocyclically through the control steps during the actuation of the contact28. In connection therewith, indicator means such as colored lamps forwater and air, respectively, may be provided on the instrument carrier 3for each instrument provided with a coolant spray device for indicatingthe actual control step for the water-air combination.

Thus, by means of the coolant control device 32 the composition of thecoolant may be controlled individually for different instruments. Inconnection with the individual control, the contacts 32a and 32b in theinstrument block may be connected to the coolant control device througha selector device 32c by means of which the number and order ofsuccession of the control steps as well as the water-air combination tobe associated with each step may be individually adjusted for theinstrument in question.

As an example, the number of control steps may be limited to be smallerthan the maximum four possible steps, and the cyclic order of successionof the steps which is run through by energization from the coolantcontrol device may be changed, so that the control cycle for aninstrument may comprise, for example, the steps no coolant, water andair, water alone, and air alone in order of succession and for anotherinstrument the steps air alone and water and air in order of succession.The selector device 32c may, in principle, be constituted by a multiswitch having a number of positions corresponding to the number ofdesired possibilities for different control cycles.

In this connection, the coolant control device may be constructed so asto allow individual adjustment for each instrument of a particular runof the control steps for that instrument as a starting step when puttingthe apparatus into operation.

The instrument blocks 20, 21 and 22 are connected with the instrumentselector device 24 in the same manner as the instrument block 19 and maybe energized from the energizing and control means 31, the coolantcontrol 32 and the air blow energizing device 31a. With the constructionof the instrument selector device 24 described in the foregoing, it willbe recorded therein at any time which of the possible lifted instrumentis selected for energization, so that a corresponding identificationsignal is made available for the input control unit 30.

The construction and function of the control circuit in FIG. 2 describedin the foregoing may without difficulty be realized by means ofconventional logic circuits constructed from separate components. In apreferred embodiment, however, the control circuit 23 comprises amicroprocessor as a central control unit incorporating the functions ofthe instrument selector device 24, the mode switching device 25, the twoinput control units 30 and 36, the coolant control device 32, and thetiming device 49, so that these devices do not occur physically asseparate units. Such a microprocessor will be connected to the fourinstrument blocks 19 to 22 and the common operator unit 17, as well asthe energizing and control means 31, the alarm device 35 and thefunction energizing devices 37 to 39 and possibly 45 in the controlcircuit 23.

In principle, the overall function of the control circuit will be thesame by use of a microprocessor as in case of a control circuit built upof separate logic circuits and will be explained in the following bymeans of the flow chart in FIG. 3.

P₁ is a program loop, by means of which the microprocessor continuouslyscans the four instrument blocks 19 to 22. For each instrument block itis asked by Q₁ whether a lift-off signal occurs. If this is not thecase, it is asked in the operation memory of the microprocessor at Q₂whether lift-off signals have been detected for one or more of the otherinstrument blocks during the previous complete scan. If so, the programroutine is stopped for the instrument in question.

If, on the contrary, it is detected by Q₁ that a lift-off signal occurs,it is asked in the operation memory of the microprocessor whether anyother instrument block has been selected for energization. If so, ablocking of the instrument in question, in this case the instrumentblock 19, is established at C₁, and the program routine in question isstopped.

If it is detected at Q₃ that no other instrument has been selected, itis asked in the operation memory of the microprocessor whether thecontrol member of the operator unit assumes its home position. Only ifthis is the case, the possibility is open for selection of theinstrument block 19 for energization, and the apparatus is switched tothe first mode of operation at C₂. Thereby, a program loop P₂ isinitiated, in which it is first asked at Q₅ whether a voltage signalfrom the voltage divider 29 in FIG. 2 occurs, i.e. whether a horizontalmovement in one direction or the other of the control member 18 out ofthe central position has been performed, If so, it is asked at Q₆ by useof the operation memory of the microprocessor whether the selectedinstrument is a motor driven drilling instrument with two directions ofrevolution and variable speed. If the answer is in the affirmative, thesign of the voltage signal is asked for at Q₇, i.e. whether the controlmember 18 has been moved to the side corresponding to counter-clockwiserotation of the drilling instrument in question. If so, the alarm device35 is actuated at C₃. Thereafter, or if it has been detected at Q₇ thatthe control member has been moved to the right corresponding toclockwise rotation of the instrument, as well as in the case of anegative answer at Q₆, it is asked at Q₈ by use of the operation memoryand timing unit of the microprocessor whether the duration of themovement of the control member has exceeded the above mentionedprescribed minimum time. If so, the instrument is energized at C₄together with the accompanying coolant spray with the water-aircombination adjusted by means of the coolant control device.Furthermore, a speed control dependent on the length of the movement ofthe control member 18 out of the central position is initiated.

If, on the contrary, it is detected at Q₈ that the minimum time has notbeen exceeded, the above mentioned air-blow is energized at C₅ which mayserve to dry a cavity. This air blow may be continuously prolonged byrepeated horizontal movements of short duration of the control member 18in on direction or the other out of the central position.

If it is detected at Q₅ that no voltage signal occurs from the voltagedivider 29 corresponding to no horizontal movement of the control member18 which is, thus, assuming the central position, it is asked at Q₉whether closure of the contact 28 corresponding to vertical movement ofthe control menber 18 occurs. If so, the coolant control device 32 isactuated at C₆ to change the water-air combination of the coolant to thefollowing control step in the control cyclus adjusted for the instrumentin question by means of the selector device 32c in FIG. 2, andsimultaneously a time measurement is initiated at C₇. Thereafter, it isasked at Q₁₀ whether closure of the contact has exceeded the minimumtime, and if so, a further change to the next following control step isinitiated at C₆, whereby the control steps are cyclically passed, aslong as the contact 28 is kept closed with time intervals between thechanges corresponding to the predetermined minimum time.

Also in an embodiment using a microprocessor, this device may beprogrammed so that a predetermined control step in the cyclus adjustedfor the instrument in question is chosen as a start step when puttingthe apparatus into operation.

If no vertical movement of the control member 18 has been detected at Q₉corresponding to the control member assuming exactly the centralposition, it is asked at Q₁₁ for a drilling instrument operating withcoolant spray by means of the operation memory of the microprocessorwhether a voltage signal from the voltage divider 29 of a longerduration than the prescribed minimum time has been detected in thepreceeding scan cycle for this instrument. If so, an air-blow isautomatically energized at C₈ preferably with two air-blows of differentduration.

If it has been detected at Q₂ that no other instrument has been liftedoff corresponding to all instruments 4 to 7 assuming their respectivepositions in the instrument carrier 3, a program loop 3 is initiated, inwhich the apparatus is first switched to the second mode of operation atC₉. Thereafter, it is asked at Q₁₂ in the same manner as at Q₅. If ahorizontal movement of the control member 18 out of the central positionis detected thereby, it is asked at Q₁₃ whether the movement is to theleft. Dependent on the fact whether this is the case or not, the twoseparate auxiliary functions or set of auxiliary functions such asdescribed in the foregoing are energized, so that in case of movement ofthe control member to the left, the function energizing device 37 inFIG. 2 is actuated, and in case of movement to the right actuation ismade of both function energizing devices 37 and 38 in FIG. 2 at C₁₀ andC₁₁ respectively. If no horizontal movement of the control member isdetected at Q₁₂, it is asked at Q₁₄ in the same manner as at Q₉, and atdetection of a vertical movement of the control member 18 a thirdseparate auxiliary function is generated at C₁₂ such as described in theforegoing by actuation of the function energizing device 39 in FIG. 2.

As shown in dashed lines in FIG. 3, the programme loop P₃ may besupplemented with a further loop corresponding to the above mentionedpossibility of an inwards movement of the control member. If it isdetected at Q₁₄ that no vertical movement of the control member occurs,it is asked at Q₁₅ whether such an inwards movement occurs and, if so, afourth separate auxiliary function is energized at C₁₃ by actuation ofthe function energizing device 45 in FIG. 2.

FIG. 4 shows a modification of the dental apparatus particularlyintended for producing an automatic air blow after each operation of adrilling instrument.

In FIG. 4, which shows only the details necessary for understanding theinvention, there is attached to the shaft of a drilling instrument 101,which in the embodiment shown is powered by an air turbine, a waterspraying device 102 on one hand and an air blowing device 103 on theother hand, said devices cooperating for spraying a coolant composed ofwater and air during operation of the drilling instrument 101.

Compressed air is supplied to the air turbine of the drilling instrument101 by means of a magnet valve 104,which is opned by a signal V_(i)supplied through a contact 105, which is closed by means of anenergizing signal from an instrument energizing device 106.Simultaneously, this signal from the instrument energizing device 106 issupplied to a water spray energizing device 107 and an air blowenergizing device 108, whereby contacts 109 and 110 are closed to supplyopening signals V_(v) and V₁ to magnet valves 111 and 112, respectively,which are thereby opened for the supply of water and air, respectively,to the water spraying device 102 and the air blowing device 103 toproduce a coolant spray during the operation of the instrument.

In the example illustrated in which the drilling instrument 101 iscontrolled by an on-off control, the energizing signal from the circuit106 is produced by means of an operator unit 113 such as a foot-contacthaving a control member 114, which is movable out of a home positionagainst spring action.

The operator unit 113 may comprise, for example, a normally open contact115, which is closed as soon as the control member 114 leaves the homeposition shown, whereby an input signal is supplied to a timing device116 to which the instrument energizing device 6 is connected at anoutput 117.

The timing device 116 is constructed to measure the duration of theclosure of the contact 115 corresponding to the movement of the controlmember 114 out of the home position so that only when the movement ofthe control member 114 exceeds a prescribed minimum time a signal issupplied at the output 117 for actuating the instrument energizingdevice 106.

For automatic production of a blow of pure air at the return of thecontrol member 114 to the home position subsequent to movement out ofthis position, the air blowing device 103 is connected in the embodimentshown to a separate air supply having a higher pressure than used forthe supply of air to the coolant by means of the magnet valve 112. Thispure air blow is controlled by a separate magnet valve 118, which isactivated by closure of a contact 117 controlled by a separate air blowenergizing device 120 having two signal inputs 121 and 122, which areconnected individually to outputs 123 and 124 of the timing device 116.However, the selective actuation of the pure air blow through the device103 may also take place by means of the same air blow energizing device108, which controls the supply of air through the coolant.

After return of the control member 114 to the home position a first or asecond control signal is supplied from the timing device 116 to saidinputs 121 and 122 of the air blow energizing device 120 in dependenceon the duration of the closure of the contact 115 resulting frommovement of the control member out of the home position having a shorteror longer duration than said prescribed minimum time.

In response to this signal on inputs 121 and 122 the air blow energizingdevice 120 generates either a first or a second opening signal for thecontact 119. The first opening signal generated in response to thesignal on the input 121 and caused subsequent to a short movement of thecontrol member 114 not resulting in actuation of the instrumentenergizing device 106 consists preferably of a single pulse having aduration of 2 seconds, for example, whereas the second opening signalgenerated in response to a signal on the input 122 and caused by thereturn of the control member 114 to the home position subsequent tooperation of the drilling instrument 101 consists preferably of at leasttwo succeeding opening pulses of different duration such as a shortpulse having a duration of 0.5 second followed by a longer pulse havinga duration of 2 seconds. The air blow caused by the first short openingpulse will blow away droplets of water contained in the coolant sprayedduring operation of the drilling instrument, whereas the following airblow will cause efficient drying of the cavity. The minimum duration ofthe movement of the control member 114 out of the home positionprescribed as a condition for energization of the drilling instrument101 may amount, for example, to 0.5 second. Thus, the above-mentionedair blow caused by a short movement of the control member 114 may becontinuously extended by repeated short movement of the control member114 within an actuation time corresponding to the duration of theabove-mentioned single opening pulse.

As shown in the drawing, since the control member 114 of the operatorunit 113 may be movable to both sides out of the central home position,the first control signal appearing at the output 123 of the timingdevice 116 as result of a short movement of the control member 114 maybe utilized either for energizing pure air blow as described in theforegoing by movement of the control member 114 to one side such as tothe right or for energizing a flush spray consisting of a combination ofwater and air. For this purpose, the water spray energizing device 107may be connected to the above-mentioned output 123 through a contact125, which is opened by movement of the control member 114 to said oneside for energizing a pure air blow and closed by movement of thecontrol member 114 to said other side, in this case to the left, whereasin the central position the contact 125 will be open or closed dependenton the side to which the control member 114 has been moved beforehand.

In response to the first control signal supplied at output 123 of thetiming device 116 the water spray energizing device 107 generates anopening signal for the magnet valve 111 of the same duration as theabove-mentioned first opening signal for the magnet valve 118.

The example shown and described represent a schematical and simplifiedembodiment of a dental apparatus according to the invention. Usually adental apparatus will comprise several instruments connected to a commoncontrol circuit and a common operator unit having a control member usedfor controlling all the instruments, whereby an instrument selectordevice influenced by removal of instruments from an instrument carrierwill prevent energization of more than one instrument at a time. In thiscase also the air blow generated according to the invention subsequentto operation of a drilling instrument may be realized for severalinstruments in the same dental apparatus, such as a drilling instrumentpowered by an electric motor with a variable rotational speed inaddition to an air turbine powered instrument.

Since such a dental apparatus may be constructed for control of thewater-air combination of the coolant, the automatic air blow accordingto the invention may be realized so that said second opening signal isonly generated after spraying of a coolant comprising water. For thispurpose a coolant control device 126 may by connected to the water sprayand air blow energizing devices 107 and 108 for adjusting thecombination of water and air in the coolant and the air blow energizingdevice may be constructed to block for supply of said second openingsignal to the magnet valve 118, when the coolant control device 126 isadjusted to influence the water spray energizing device 107 to block forthe supply of water to the coolant.

The control of the air blow provided in accordance with the inventionsubsequent to operation of a drilling instrument may be realized bymeans of a control circuit built up in a conventional manner of separatelogic components or it may be incorporated in a microprocessor controlof a dental apparatus such as explained in the foregoing.

It will appear from the foregoing that a wide-extending simplificationand automatization of the operation functions to be carried out by thedentist is obtained with the dental apparatus according to theinvention, since auxiliary functions not related to the instrumentoperation are energized or carried out solely by operation of the commonoperator unit 17 with the control member 18.

As far as the actual auxiliary functions are concerned which are to becarried out in the second mode of operation for certain movements of thecontrol member 18 of the operator unit 17, numerous modifications may bemade within the scope of the invention relative to the examples of suchfunctions described in the foregoing.

We claim:
 1. A dental apparatus comprising at least one drillinginstrument and an operator unit with a control member which is movableagainst spring action out of home position for energizing andcontrolling said drilling instrument, an instrument energizing deviceconnected between said drilling instrument and said operator unit, awater spraying device and an air blowing device provided on saiddrilling instrument, water and air supplies connected with said waterspraying and air blowing devices, valve devices arranged between saidwater and air supplies and said water spraying and air blowing device,and water spray and air blow energizing devices connected to said valvedevices and said instrument energizing device for producing a coolantspray during operation of the instrument, a selectively actuatable airblow energizing device with an associated valve device being provided atleast for said air blowing device, said selectively actuatable air blowenergizing device being connected to said operator unit forautomatically supplying an opening signal to its associated valve devicein response to the control member of said operator unit returning tosaid home position following a movement out of said position.
 2. Adental apparatus as claimed in claim 1, wherein a timing device isconnected between said selectively actuatable air blow energizing deviceand said operator unit for measuring the duration of the movement of thecontrol member out of said home position and said selectively actuatbaleair blow energizing device is constructed to produce first or secondopening signals for said valve device in response to the duration of themovement of the control member being shorter or longer, respectively,than a prescribed minimum duration.
 3. A dental apparatus as claimed inclaim 2, wherein said first opening signal comprises a single openingpulse, whereas said second opening signal somprises at least twosucceeding opening pulses of different duration.
 4. A dental apparatusas claimed in claim 2, wherein also the water spray energizing device isconnected to said timing device for producing an opening signal for itsassociated valve device at a shorter duration of the movement of saidcontrol member than said prescribed minimum duration.
 5. A dentalapparatus as claimed in claim 4, wherein the control member of theoperator unit is movable in opposite directions out of said homeposition, a contact controlled by the operator unit being disposedbetween the water spray energizing device and the timing device forinterrupting the connection there between by movement of said controlmember in one of said directions.
 6. A dental apparatus as claimed inclaim 2, wherein said water spray and said air blow energizing devicesare connected to a coolant control device for adjusting the mixing ratioof water to air in the coolant spray, said selectively actuatable airblow energizing device being constructed to block for supplying saidsecond opening signal to the associated valve device by adjustment ofsaid coolant control device for actuating said water spray device toblock for the supply of water into the coolant.